The present invention relates to a tripod joint. The tripod joint has an outer joint part with three circumferentially distributed, axis-parallel recesses forming circumferentially opposed tracks. An inner joint part with a star-shaped cross-section and three circumferentially distributed arms engages the recesses in the outer joint part. The arms support roller assemblies. Each roller assembly has at least one inner ring and an outer roller. The inner ring is angularly movable relative to the arm and axially movable relative to the arm axis. A rolling contact bearing is between the outer surface of the inner ring and the inner surface of the outer roller with the outer surface of the outer roller rolling directly on the tracks.
With conventional tripod joints, the tripod rollers, with reference to the arm axis, are axially movable and rotatably arranged on their tripod arms. In consequence, with a joint rotating in the articulated condition, the roller axis oscillatingly moves out of its originally perpendicular position relative to the axis of the outer joint part. This movement occurs every time the joint rotates between two end positions which, in each case, correspond to the joint articulation angle. In the process, the movement of the roller surface on the outer roller relative to the track in the outer joint part subjected to loads during the introduction of torque, in addition to the rolling component as a result of the articulation angle, has a sliding component which leads to vibration excitations out of the joint.
These disadvantages have already been overcome in the case of joints of the type where the roller axis is permanently held in a perpendicular position relative to the longitudinal axis of the outer joint part. Here, the rollers carry out purely oscillating rolling movements when the joint rotates in the articulated condition. The sliding movement takes place entirely between the respective tripod arm and a non-rotating, possibly multi-component, inner ring.
In order to ensure that the angularly constant position of the roller assembly is maintained with reference to the outer joint part and with the orientation of its longitudinal axis remaining unchanged, it is necessary to provide special supporting faces for the roller assembly in the outer joint part. JP 2 135 719 U illustrates this type of joint. In this disclosure, the inner ring of a roller assembly, with reference to its axis, is provided with a radially enlarged collar. The collar, with reference to the joint axis, rests against guiding edges of the tracks in the outer joint part. When viewed radially, the collar is substantially rectangular thereby preventing the inner ring from rotating around the arm axis on the one hand and the roller assembly from tilting with reference to the axis of the outer joint part on the other hand. The disadvantages of this design refer to the complicated design of the inner ring and the multi-component design of the roller assembly.